The goal of this Program Project is understanding the DNA sequence organization of the eukaryotic genome. It appears evident that the structural basis of gene regulation in higher organisms lies in the specific organization of genomic DNA sequences. Many of the individual research projects included involve recombinant DNA clones. Most studies concern genomic sequence organization of rat, sea urchin, Drosophila, Antheraea polyphemis DNAs. Laboratories contributing to the Program Project are those of Normal Davidson, Eric Davidson, Tom Maniatis, James Bonner, and Roy Britten. The Project is divided into four task areas. These are: I) Development of new technology and improvement of existing technology needed for DNA sequence organization research, II) analysis of sequence organization in the vicinity of particular genes or genetic loci, III) investigations concerned with the organization, character, and evolution of repetitive sequences and, IV) miscellaneous sequence organization problems. Specific research projects include: in Task Area I measurement of deletions and translocations in two-dimensional gel display of restriction enzyme digests of animal DNA, further investigations of RNA-DNA and DNA-DNA renaturation kinetics, and development of rapid methods for mapping Drosophila salivary glands; in Task Area II isolation of sequences for y chromosome male fertility factors, the white locus and the bithorax genes of Drosophila; isolation and sequence analysis of genomic regions including structural genes from rat, sea urchin, and Drosophila genomes; isolation and sequence analysis of regions including the chorion gene family in A. polyphemis; in Task Area III analyses of long repetitive sequences in sea urchin and rat genomes; sequence determinations and analysis of global distribution of interspersed repeats; studies of evolutionary processes affecting interspersed repeats; in Task Area IV measurement of single copy sequence polymorphism, analyses of sequences of tandem reverse repeats, and DNA transformation of drosophila embryos.